Commit 3897df4c authored by Matthew Brost's avatar Matthew Brost Committed by John Harrison
Browse files

drm/i915/guc: Introduce context parent-child relationship 



Introduce context parent-child relationship. Once this relationship is
created all pinning / unpinning operations are directed to the parent
context. The parent context is responsible for pinning all of its
children and itself.

This is a precursor to the full GuC multi-lrc implementation but aligns
to how GuC mutli-lrc interface is defined - a single H2G is used
register / deregister all of the contexts simultaneously.

Subsequent patches in the series will implement the pinning / unpinning
operations for parent / child contexts.

v2:
 (Daniel Vetter)
  - Add kernel doc, add wrapper to access parent to ensure safety
v3:
 (John Harrison)
  - Fix comment explaing GEM_BUG_ON in to_parent()
  - Make variable names generic (non-GuC specific)
v4:
 (John Harrison)
  - s/its'/its/g

Signed-off-by: default avatarMatthew Brost <matthew.brost@intel.com>
Reviewed-by: default avatarJohn Harrison <John.C.Harrison@Intel.com>
Signed-off-by: default avatarJohn Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211014172005.27155-8-matthew.brost@intel.com
parent 9409eb35

drivers/gpu/drm/i915/gt/intel_context.c

+29 −0
Original line number Diff line number Diff line
@@ -403,6 +403,8 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine) 


	INIT_LIST_HEAD(&ce->destroyed_link);



	INIT_LIST_HEAD(&ce->parallel.child_list);



	/*

	 * Initialize fence to be complete as this is expected to be complete

	 * unless there is a pending schedule disable outstanding.
@@ -417,10 +419,17 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine) 


void intel_context_fini(struct intel_context *ce)

{

	struct intel_context *child, *next;



	if (ce->timeline)

		intel_timeline_put(ce->timeline);

	i915_vm_put(ce->vm);



	/* Need to put the creation ref for the children */

	if (intel_context_is_parent(ce))

		for_each_child_safe(ce, child, next)

			intel_context_put(child);



	mutex_destroy(&ce->pin_mutex);

	i915_active_fini(&ce->active);

	i915_sw_fence_fini(&ce->guc_state.blocked);
@@ -537,6 +546,26 @@ struct i915_request *intel_context_find_active_request(struct intel_context *ce) 
	return active;

}



void intel_context_bind_parent_child(struct intel_context *parent,

				     struct intel_context *child)

{

	/*

	 * Callers responsibility to validate that this function is used

	 * correctly but we use GEM_BUG_ON here ensure that they do.

	 */

	GEM_BUG_ON(!intel_engine_uses_guc(parent->engine));

	GEM_BUG_ON(intel_context_is_pinned(parent));

	GEM_BUG_ON(intel_context_is_child(parent));

	GEM_BUG_ON(intel_context_is_pinned(child));

	GEM_BUG_ON(intel_context_is_child(child));

	GEM_BUG_ON(intel_context_is_parent(child));



	parent->parallel.number_children++;

	list_add_tail(&child->parallel.child_link,

		      &parent->parallel.child_list);

	child->parallel.parent = parent;

}



#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)

#include "selftest_context.c"

#endif

drivers/gpu/drm/i915/gt/intel_context.h

+41 −0
Original line number Diff line number Diff line
@@ -44,6 +44,47 @@ void intel_context_free(struct intel_context *ce); 
int intel_context_reconfigure_sseu(struct intel_context *ce,

				   const struct intel_sseu sseu);



static inline bool intel_context_is_child(struct intel_context *ce)

{

	return !!ce->parallel.parent;

}



static inline bool intel_context_is_parent(struct intel_context *ce)

{

	return !!ce->parallel.number_children;

}



static inline bool intel_context_is_pinned(struct intel_context *ce);



static inline struct intel_context *

intel_context_to_parent(struct intel_context *ce)

{

	if (intel_context_is_child(ce)) {

		/*

		 * The parent holds ref count to the child so it is always safe

		 * for the parent to access the child, but the child has a

		 * pointer to the parent without a ref. To ensure this is safe

		 * the child should only access the parent pointer while the

		 * parent is pinned.

		 */

		GEM_BUG_ON(!intel_context_is_pinned(ce->parallel.parent));



		return ce->parallel.parent;

	} else {

		return ce;

	}

}



void intel_context_bind_parent_child(struct intel_context *parent,

				     struct intel_context *child);



#define for_each_child(parent, ce)\

	list_for_each_entry(ce, &(parent)->parallel.child_list,\

			    parallel.child_link)

#define for_each_child_safe(parent, ce, cn)\

	list_for_each_entry_safe(ce, cn, &(parent)->parallel.child_list,\

				 parallel.child_link)



/**

 * intel_context_lock_pinned - Stablises the 'pinned' status of the HW context

 * @ce - the context

drivers/gpu/drm/i915/gt/intel_context_types.h

+21 −0
Original line number Diff line number Diff line
@@ -220,6 +220,27 @@ struct intel_context { 
	 */

	struct list_head destroyed_link;



	/** @parallel: sub-structure for parallel submission members */

	struct {

		union {

			/**

			 * @child_list: parent's list of children

			 * contexts, no protection as immutable after context

			 * creation

			 */

			struct list_head child_list;

			/**

			 * @child_link: child's link into parent's list of

			 * children

			 */

			struct list_head child_link;

		};

		/** @parent: pointer to parent if child */

		struct intel_context *parent;

		/** @number_children: number of children if parent */

		u8 number_children;

	} parallel;



#ifdef CONFIG_DRM_I915_SELFTEST

	/**

	 * @drop_schedule_enable: Force drop of schedule enable G2H for selftest